The Coalition split over tackling knife crime will be laid bare next week when Conservative and Liberal Democrat ministers clash over moves to toughen penalties for carrying blades.

Their differences will come to a head when the Commons votes on a Tory MP’s call for anyone caught twice with a knife to face an automatic jail sentence.

Conservative ministers support the principle of the move, but it is opposed by the Liberal Democrats.

After they failed to reach an agreed position, Tory ministers have been instructed to abstain, while the vast majority of Conservative backbenchers including parliamentary private secretaries are expected to support the move.

Meanwhile, Lib Dem MPs including ministers will vote against the proposed sanction. It is likely to be approved with Labour support, meaning it has a good chance of becoming law.

A Tory source said: “The Conservatives have always made clear we want to do more to tackle knife crime. The Commons will vote next week on an amendment to jail people caught carrying a knife on more than one occasion.”

But a Lib Dem source countered: “We believe in giving judges the flexibility to use their expertise and judgement, based on the facts of each case. Prison is often going to be the right option and violent offenders who are a danger to the public ought to be behind bars but that should be for judges to decide.”